Drying oil composition and a process for improving particle board



United States Patent Oil-lee Patented Jan. 10, 1967 3,297,603 DRYING 01L COMPOSITION AND A PROCESS FOR IMPROVING PARTICLE BOARD Gerald Duane Mase, Homewood, Ill., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Filed Mar. 29, 1963, Ser. No. 269,170 4 Claims. (Cl. 26017.3)

This invention relates to compositions useful in the manufacture of particle board, and in particular, compositions which improve the water resistance of the particle board.

Particle board is generally considered a descriptive term for relatively dense boards, usually in panel form, made from dry wood particles that have been coated with a binder and then formed and bonded to shape by pressure and heat as described in a publication entitled Particle Board, dated February 1959, issued by the US. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison 5, Wisconsin. Particle board may be used as core material in place of solid, edge-glued lumber for furniture panels, flush doors and veneered wall panels. It has both interior and exterior applications, although commonly used more for interior application at present,

Usually the particle board is prepared from wood fibers which have been dried to a moisture content in the order of about 2-10% by weight. The wood fibers are then added to a blender, and a binder, usually a water dispersable urea-formaldehyde known in the art, is applied to the fi-bers. Usually a catalyst for the urea-formaldehyde (such as ammonium sulfate) is also present. Other materials such as wax may also be applied at this point, although too much Wax adversely affects the strength of the particle board and the later painting of the particle board. The output from the blender is then fed to a storage container from which the mixture of wood particles and binder are formed into a loose mat or felt. The felt is fed to a press and treated therein at pressures in the order of 250-500 p.s.i. and at temperatures in the order of 250-400 F. for 5-10 minutes. The output from the press is then cut to size and sent to storage.

A common problem with particle board concerns its resistance to moisture. Usually, the particle board is prepared for an urea-formaldehyde binder and exhibits a Water resistance which is not entirely satisfactory. In some instances, phenolic binders have been employed to improve the water resistance of the particle board; however, the phenolic binders are considered expensive and therefore are not practical for many applications.

The need to improve the water resistance of the particle board is important. As noted from the above described uses, the resistance of particle board to moisture affects the durability of many of the products produced from the particle board.

An object of this invention is to provide particle board with improved water resistance. A further object is to provide compositions which impart improved water resistance of the particle board. Other objects and advantages of the invention will be apparent from the detailed description herein.

It has been discovered that the water resistance of a particle board employing a urea-formaldehyde binder is improved when the particle board is prepared from a composition comprising about 10-60 weight percent of a hydrocarbon polymer, about 10-75 weight percent of a vegetable drying oil, about 5-50 weight percent of a hydrocarbon solvent oil, and a small amount of a suitable metal drier. Usually the composition is applied to the wood fibers in an oil-in-Water emulsion which comprises a major amount of the above composition and water, and a minor amount of an emulsifier. The application of the emulsion is usually carried out in the presence of the urea-formaldehyde binder, and preferably during the treatment of the wood fibers with the urea-formaldehyde binder.

As described above, the invention is directed to (1) a composition for improving the water resistance of particle board, (2) a preferred oil-in-Water emulsion for the application of the composition to the wood fibers which are used in the preparation of the particle board, and (3) a process of manufacturing particle board employing the above compositions,

The composition which imparts improved water resistance to the particle board includes about 10-60% weight percent of a hydrocarbon polymer, and preferably about 25-50 weight percent. The hydrocarbon polymer generally has an iodine number between about 120 and 350 and preferably about 150-200. Therefore, the hydrocarbon polymer may also be described as a hydrocarbon drying oil. Usually it has an initial boiling point of about ZOO-300 F., with at least 50% (weight), and preferably -90% (weight) boiling at a temperature higher than about 400 F. Examples of hydrocarbon drying oils are Gray tower polymer, clay tower polymer, polybutadiene, HF-oil, and the like. A suitable drying oil can be prepared by the polymerization of unsaturated liquid hydrocarbon fractionations produced in the high temperature pyrolysis (1200-l500 F. at short contact times of 0.01 to 10 seconds) of gas or liquid hydrocarbons. Drip oils, sometimes known as dripolene, are produced during the pyrolysis. These oils are rich in olefinic and diolefinic hydrocarbons and essentially free of saponifiable materials. An example of one of such oils boils between about 200 and 700 F. and has an iodine number of 150-500. The

drip oils may be polymerized either thermally or catalytically to yield the product hydrocarbon drying oil. After polymerization is effected, the product is stripped of low boiling monomeric materials to yield a product hydrocarbon drying oil that is used in the particle board.

The desired composition also includes about 10-75 weight percent of a vegetable drying oil, and preferably about 20-40 weight percent. The vegetable drying oil may be a naturally occurring oil such as raw linseed oil, soybean oil, tung oil, castor oil, perilla oil, safi lower oil, oiticica oil, walnut oil and the like. It may also be a processed vegetable drying oil which has been bodied by ageing, boiling, or otherwise heating so that coplymers are formed; oxidized oils which have been blown with air; and isomerized oils. The preferred vegetable drying oils are those naturally occurring since they are readily available, and especially preferred is oiticica oil.

Suitable hydrocarbon solvent oils include petroleum oils, such as for example solvent extracts of lubricating oils, catalytic cyclic oils, gas oils, and the like. Usually the solvent oil is a high boiling material. At least 50% by weight, and preferably -100% by weight of the solvent should boil at a temperature not lower than about 350 F. In addition, the solvent should not be one that boils above 750 F. Usually, the solvent oil is present in the composition in about -50 weight percent and preferably 30-50 weight percent.

The composition also includes a small amount of a suitable metal drier in order to promote the rate of drying of the composition. Suitable driers are usually a metal salt of a fatty acid such as naphthenic acid, stearic acid, oleic acid, tall acid and the like. Common metals include iron, zinc, aluminum, manganese, cobalt and lead. Desirable driers include iron naphthenate and iron tallate, with iron naphthenate being preferred. The drier may be employed in an amount between about 0.1 and 10% by weight, and preferably 0.251.5% by weight of the composition. Usually a small amount such as about 0.5% by weight is sufiicient.

The composition is prepared by mixing the components together simultaneously or in any desirable sequence. Usually, the metal drier is added as the last component and generally within a short time before use in order to reduce oxidation problems.

Generally from about 115% by weight (of dry wood fibers) of the composition is applied to the wood fibers and preferably about 25% weight.

In addition to the urea-formaldehyde binder, the formulation for the particle board optionally includes some wax. Commonly the wax is present in the order of about /2 %-1% by weight. The wax is utilized to improve the water resistance of the particle board and How characteristics of the wood particles during pressing; however, its presence is limited by the adverse affect of high amounts of wax on the strength of the particle board. Excessive wax also adversely affects subsequent coating operations such has painting.

The application of the composition (hydrocarbon polymer, vegetable drying oil, hydrocarbon solvent and metal drier) to the wood fibers in the presence of the -urea formaldehyde binder, may be carried out by more than one method. Suitable methods include the direct spraying of the composition on the wood fibers in the presence of the urea-formaldehyde binder at a suitable temperature whereby the composition is in a fluid form. Another and preferable procedure is by spraying an oil-in-water emul sion in the presence of the urea-formaldehyde binder. Commonly and advantageously, the application is carried out during the treatment of the wood chips with the ureaformaldehyde binder. The composition should not be applied to the particle board as a post treatment additive (such as wallboard saturant) because the absorption of the composition tends to be excessive, the strength of the particle board is reduced, and the cost of the treatment is significantly increased.

The preferable oil-in-water emulsion comprises a major amount of the composition (hydrocarbon polymer, vegetable drying oil, hydrocarbon solvent, and metal drier) and water, and a minor amount of an emulsifier. The utilization of the emulsion increases the effective surface area of a given amount of the oil portion of the emulsion and improves the aflinity of the wood particles for the oil portion. In general, the oil and water are in a weight relationship determined by the factors which promote the formation of an oil-in-water emulsion. Commonly about 30-70 weight percent of the oil-in-water emulsion is oil.

The emulsifier includes the nitrogen containing emulsifiers such as those derived from ammonia or amine. Mixtures of ammonium hydroxide and a non-saturated fatty acid such as tall oil fatty acid are very desirable and preferred. This mixture is present in an amount from about 2-10 weight percent of the emulsion and preferably 4-8 weight percent. One surprising benefit derived from an emulsifier which comprises a mixture of ammonium hydroxide and an unsaturated fatty acid is that the emulsifier also serves to replace the catalyst for promoting the curing of the urea-formaldehyde binder.

The above described emulsion is present in the particle board formulation in an amount equivalent to about 230% by weight of dry woo-d fibers and preferably 4- 15 by weight based on emulsion containing about 60% of the oil composition.

After the treatment with the urea-formaldehyde binder and the composition or emulsion as described above, the Wood fibers are processed according to previously known procedures. Usually they are fed to a felter to produce a loose mat or felt, and then fed to a press in which temperatures in the order of 250 to 500 p.s.i. and times in the order of 5 to 10 min. are employed.

After the pressing operation, the particle board is commonly cut into predetermined sizes and sent to storage.

The following examples illustrate some of the embodiments of this invention. It will be understood that these are for illustrative purposes only and do not purport to be wholly definitive with respect to conditions or scope.

Example I An oil-in-water emulsion was prepared from approximately 22% by weight of a liquid hydrocarbon polymer (having an iodine number of 168, a viscosity of 936 SSU at 210 F., and a specific gravity of 1.072), 22% by weight of a catalytic cycle oil (having a boiling range of about 520-750 F., and a viscosity of about 54 SSU at F.), 15 by weight of oiticica oil, 0.3% by weight of iron naphthenate (containing about 6% iron by weight), 4% by weight of tall oil fatty acid, 2.0% by weight of an aqueous ammonium hydroxide solution (28-30% by weight of ammonia), and 33.7% by weight of water. A mixture of all but the last two materials was prepared and heated to approximately 180 F. A dilute solution of ammonium hydroxide was also prepared from the concentrated solution and water, the latter at 180 F. Under vigorous mechanical agitation, the ammonium hydroxide solution was slowly added to the oil portion. After the inversion point of the emulsion was reached, the remaining water was added more rapidly. A-n urea-formaldehyde binder was prepared from a commercial urea-formaldehyde (65% NVM) CRSH. The commercial product was the reaction product of urea and formaldehyde having a pH of about 8.1, a viscosity at 73 F. of about 700 centipoises, and a specific gravity of about 1.29. The binder formulation contained approximately 80% by weight of the commercial urea-formaldehyde and the remainder was made up of urea (approx. of remainder), water and an ammonium sulfate catalyst.

The urea-formaldehyde binder was then mixed with a wax emulsion containing about 46% by weight of solids and marketed as Paracol 404 N. The wax portion of the emulsion was characterized as a paratfin having a melting point of about 135 F. The mixture of binder and wax emulsion was sprayed on wood fibers in a rotating bafile drum using a spray gun. The oil emulsion was then sprayed on the wood fibers.

In carrying out the above application of the binder, wax emulsion, and oil emulsion to the wood fibers, four compositions were individually applied to wood fibers. The amount of the urea-formaldehyde wax emulsion and oil emulsion for each is shown in Table I below.

The treated wood particles were then formed into a mat and pressed into a inch thick particle board sample with a density of approximately 43 lbs. per cubic foot. The press conditions used in this work were a temperature of approximately 325 F., a pressure of approximately 360 p.s.i. as a maximum, and a time of approximately 10-12 minutes. The press was an electrically heated, hydraulically operated laboratory press. Press stops were used to control thickness and density.

The strength, water resistance and other properties of the particle board samples were then determined as shown in Table I below. The test data in Table I was obtained using the test procedures outlined in ASTM D-l037. In Table I, MOR represents the modulus of rupture, water absorption represents the weight percentage of increase in the particle board after being placed under an inch of water for approximately 24 hours, water swell represents the percentage change in thickness of the particle board after the 24 hour exposure to the water, and the linear expansion represents the percentage change in the linear 5 urea-formaldehyde-may be absent and thus a urea-formdimension of the particle board after the 24 hour exposure aldehyde having a longer pot life may be employed. to the water. The' finished particle board made with the emulsion TABLE I Density, Initial Wet MOR, Retained Water Water Linear Sample Treatment lbs/ft. MOR, p.s.i. p.s.i. Strength, Absorption, Swell, Expansion,

Percent Percent Percent Percent A 65% UF 42 .6 2, 630 2,160 82.2 12.1 4.3 0 .17 I 43 .2 2, 680 2, 270 84 .6 8.0 3 .7 0 .13 UF- I D {10.0% Emulsiom-.- 44.0 2, 170 2,040 94.0 7.5 2 .7 0.15

0.5% Wax In addition to the data in Table I, the finished particle 25 has a more attractive appearance than boards made Withboard made from the oil emulsion had a slightly darker out the emulsion. The finished surface is quite smooth surface than that of the particle board made without the and glossy. oil emulsion. The slightly darker surface Was considered Thus having described the invention, what is claimed is: attractive in appearance. 1. In the process of manufacturing particle board com- The above data in Table I demonstrates that the water prising wood particles and urea-formaldehyde binder resistance properties of the particle board are definitely wherein wood particles are first coated with the ureaimproved by the treatment with the emulsion described formaldehyde binder composition, and the coated parin Example I. ticles then consolidated and bonded together by compres- The results for particle board C demonstrate that the sion at elevated pressures and temperatures, the improveaddition of 5% by weight of the emulsion produced a ment consisting of the step of applying to the urea-formboard which exhibited improved water resistance as espealdehyde coated wood particles prior to compression cially noted by low value of 8.0% Water absorption comthereof about 1-15 weight percent, based on the dry pared to 12.1% for particle board A and B. The reweight of the wood particles, of a drying oil composition sults for particle board D also demonstrate superiority consisting essentially of (A) about 10-60 weight percent in water resistance (7.5% water absorption) over parof a hydrocarbon drying oil having an iodine number ticle board A and B. In addition, the strength retention between about 120 and 350; (B) about l0-75 weight perand water swell for particle board C and D were superior cent of a vegetable drying oil; (C) about 550 weight to the values for particle board A and B. percent of a petroleum oil solvent boiling below about Example ll 750 F. and having at least 50 weight percent thereof bOlllIlg at a temperature above about 350 F.; and (D) Particle board samples were also prepared according to from about 0.1 to about 10 percent of a metal drier. the procedure described in Example I except that the 2. The process of claim 1 further characterized by the ammonium Sulfate Catalyst for the urea-formaldehyde application of said drying oil composition to said wood binder was absent. The results for the particle board particles in the form of an oil-in-water emulsion wherein produced with oil emulsion and in the absence of the amsaid emulsion contains about 30-70 weight percent of said monium sulfate (Sample F) were then compared to the drying oil composition, from about 2-10 weight percent results from particle board samples prepared with and of anitl'ogen-containing emulsifier, and the balance water. without the ammonium sulfate catalyst (Samples D and 3. The process of claim 2 wherein said emulsifier is B, respectively). The results are shown in Table II a mixture of ammonium hydroxide and unsaturated fatty below. The test data in Table II were obtained using the acid. test procedures outlined in ASTM D-1047. 4. In the process of manufacturing particle board com- TABLE II MOR Water Density after Absorp- Water Sample Treatment lbs .ltt Wat er tion, Swell,

Soak, Percent Percent p.s.i.

D 312%iifiiihiiillijii ji 2,100 E 812g? 41 1 1, 560 20.4 8.8

{6.5% F 5.0% Oil emulsion 42.5 2,120 7.9 2.8

0.5% Wax emulsion The above results in Table II demonstrate that the prising wood particles and urea-formaldehyde binder emulsion containing the mixture of ammonium hydroxide wherein wood particles are first coated with the ureaand tall oil fatty acid served in place of the ammonium formaldehyde binder composition, and the coated parsulfate catalyst in addition to its being an emulsifier. ticles then consolidated and bonded together by compression at elevated pressures and temperatures, the improvement consisting of the step of applying to the ureaformaldehyde coated Wood particles prior to compression thereof about 510 weight percent, based on the dry weight of the wood particles, of an oil-in-water emulsion consisting essentially of (A) about 22 weight percent of a hydrocarbon drying oil having an iodine number of 168, a viscosity of 936 SSU at 210 F., and a specific gravity of 1.072; (B) about 22 weight percent of a petroleum catalytic cycle oil having a boiling range of about 10 520750 F., and a viscosity of about 54 SSU at 100 F.; (C) about 15 weight percent of oiticica oil; (D) about 0.3 weight percent of iron naphthenate; (E) about 4 weight percent of tall oil fatty acid; (F) about 2 weight percent ammonia), and the balance water.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 5/ 1955 Great Brita-in.

WILLIAM H. SHORT, Primary Examiner.

LOUISE P. QUAST, Examiner. percent of aqueous ammonium hydroxide (28-30 weight 15 E. M. WOODBERRY, Assistant Examiner. 

1. IN THE PROCESS OF MANUFACTURING PARTICLE BOARD COMPRISING WOOD PARTICLES AND UREA-FORMALDEHYDE BINDER WHEREIN WOOD PARTICLES ARE FIRST COATED WITH THE UREAFORMALDEHYDE BINDER COMPOITION, AND THE COATED PARTICLES THEN CONSOLIDATED AND BONDED TOGETHER BY COMPRESSION AT ELEVATED PRESSURES AND TEMPERATURES, THE IMPROVEMENT CONSISTING OF THE STEP OF APPLYING TO THE UREA-FORMALDEHYDE COATED WOOD PARTICLES PRIOR TO COMPRESSION THEREOF ABOUT 1-15 WEIGHT PERCENT, BASED ON THE DRY WEIGHT OF THE WOOD PARTICLES, OF A DRYING OIL COMPOSITION CONSISTING ESSENTIALLY OF (A) ABOUT 10-60 WEIGHT PERCENT OF A HYDROCARBON DRYING OIL HAVING AN IODINE NUMBER BETWEEN ABOUT 120 TO 350; (B) ABOUT 10-75 WEIGHT PERCENT OF A VEGETABLE DRYING OIL; (C) ABOUT 5-50 WEIGHT PERCENT OF A PETROLEUM OIL SOLVENT BOILING BELOW ABOUT 750*F. AND HAVING AT LEAST 50 WEIGHT PERCENT THEREOF BOILING AT A TEMPERATURE ABOVE ABOUT 350*F.; AND (D) FROM ABOUT 0.1 TO ABOUT 10 PERCENT OF A METAL DRIER. 